1978257 has 4 divisors (see below), whose sum is σ = 2637680. Its totient is φ = 1318836.

The previous prime is 1978219. The next prime is 1978267. The reversal of 1978257 is 7528791.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 7528791 = 3 ⋅2509597.

It is not a de Polignac number, because 1978257 - 2¹⁰ = 1977233 is a prime.

It is an Ulam number.

It is a D-number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1978267) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 329707 + ... + 329712.

It is an arithmetic number, because the mean of its divisors is an integer number (659420).

2^1978257 is an apocalyptic number.

It is an amenable number.

1978257 is a deficient number, since it is larger than the sum of its proper divisors (659423).

1978257 is an equidigital number, since it uses as much as digits as its factorization.

1978257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 659422.

The product of its digits is 35280, while the sum is 39.

The square root of 1978257 is about 1406.5052435025. The cubic root of 1978257 is about 125.5338659842.

The spelling of 1978257 in words is "one million, nine hundred seventy-eight thousand, two hundred fifty-seven".